Absorption Chillers: Here to Stay

From the late 1980s to the mid-1990s, the use of absorption chillers increased as a result of relatively low gas prices, CFC phaseouts, and gas utility rebates.

However, as gas prices increased, deregulation became a factor, and the commercial replacement market slowed down along with the economy, absorption markets in North America dropped sharply.

Nevertheless, absorption chiller use is currently showing strong signs of life, according representatives from Carrier, York, and Trane. In fact, with building owners increasingly looking for creative ways to save energy, it appears that absorption chillers are here to stay.

Carrier Corp.

“There has always been a place for absorption chillers for facility owners wanting to lessen their dependency on electric power, particularly in heavily-populated areas with high electric rates and/or demand charges,” says Doug Rector, product manager for Carrier Corp., Syracuse, NY.

Rector adds that with no large moving parts, the Carrier-Sanyo line of absorption chillers are quiet, making them ideal for applications that are sensitive to sound and vibration.

Among Carrier’s absorption customers are office buildings, hotels, and manufacturing facilities, as well as hospitals and universities, which often use natural gas, hot water, or steam-fired equipment. At many of these facilities, the company is seeing increased interest in cogeneration.

”Because the heat energy is often wasted, owners are looking for ways to be more creative with energy usage,” Rector says.

”For example, depending on the characteristics of the available energy source, it can possibly be used to operate a single-effect, steam, or hot water fired chiller,” he adds.

In addition, high-pressure steam can be used with a double-effect chiller, with a corresponding increase in cycle efficiency. Furthermore, a double-effect, gas-fired unit can provide both cooling and heating, thereby reducing — or possibly eliminating — the need for a boiler.

As far as Carrier’s plans with absorption chillers, Rector says that the manufacturer will soon have an even stronger presence in the marketplace

"We look forward to being able to offer our customers even more Carrier-Sanyo chiller water solutions to complement our electric-driven products,“ he says.

York International Corp.

To keep pace with its heavy-duty commercial market, York spends a lot of time in the field working with customers on how to best apply the company’s equipment to their systems.

"One of our principal strategies is to offer equipment suitable for hybrid chiller plants, which can include both electric and absorption chillers,“ says Ian Spanswick, product manager for York's Applied Chiller Group. “This is ideal for owners who carefully monitor their energy rates and want to be able to switch between electric and non-electric sources as prices fluctuate.“

Another strategy has been to work closely with customers interested in cogeneration or distributed energy generation. "Building owners who generate their own power onsite can produce their base load of power and cooling. This makes them good candidates for absorption chillers,“ adds Spanswick.

Waste heat recovery also is viewed as an important application, particularly for single-effect chillers, according to Jay Kohler, manager, Industrial Systems Engineering.

"Single effect chillers have the ability to produce cooling using waste heat streams, such as the jacket water from gas engines or the exhaust gas from gas turbines used with CHP systems. In doing so, they can significantly increase the overall plant energy efficiency,“ Kohler says. "Single effect chillers are also well-suited to recovering heat from other low temperature waste heat sources, which may be a by-product of many industrial processes."

In terms of technological advancements, Kohler says, “Absorption chillers have ‘evolved’ over the years, as they’ve become more user-friendly and efficient. They also feature improved controls and inhibitor technology components, which go into the solution to help preserve the life of the chiller.”

In addition to refining its single- and double-effect chillers, York has also worked on the development of a triple-effect absorption chiller, with funding from the U.S. Department of Energy. “Triple-effect chillers are substantially more efficient than single- and double-effect chillers,“ says Spanswick. ”For example, on a gas-fired chiller, triple effect might add up to 35% greater efficiency.“

While these triple-effect chillers have been successfully field tested, they’re currently not available for purchase. "Despite their high-efficiency, we don’t believe there is sufficient market demand at this point for their mass production,“ says Kohler. "Nevertheless, the most important point is that our research proved this technology works. This will continue to help us improve our existing products.“

Trane

Since the 1950s, Trane has been offering customers a wide variety of absorption chillers, which currently range from 100 to 1,700 tons.

"During the early 1990s, with the assistance of Gas Technology Institute, we completely redesigned our absorption line, using new technologies to increase efficiency and reliability,“ says Sherri Olson, absorption chiller product manager for Trane. "The result is our Horizon line of absorption chillers, which was a major step forward in absorption technology. For example, we added automated controls to provide a wide range of control strategies to improve performance, reliability, and operating costs.“

Trane continues to keep a close eye on the pace of the absorption market in North America and abroad. "Currently, the largest market is in China, where the Shanghai government recently launched a large-scale incentive program for the use of absorption chillers and cogeneration,“ she says.

In the U.S., Olson sees demand growing once again. Ideal applications for absorption chillers, she says, are large buildings or institutions with heavy steam or hot water loads, such as universities, which have large steam plants for heating.

"For example, during the summer, when boilers aren’t being used to their full capacity, their operation can become inefficient. By maintaining their capacity close to full load, the steam from these boilers can be used to drive absorption chillers for cooling. So when electric demand is high, using an absorption chiller can be more cost- effective.“

Olson adds that facility owners and managers have become increasingly savvy about running their facilities more effectively and efficiently. "That’s where distributed power generation and BCHP (buildings cooling, heating and power) type applications are beginning to draw a lot of attention,“ she says. "Absorption chilling from the recovered waste heat of these systems can make a lot of sense.“

In regard to Trane’s future plans for its absorption chillers, "As a building solutions provider, we want to offer our customers as many viable equipment options as possible. Absorption chillers are one of the options currently available,“ says Olson.

Winter is nearly gone. Hot weather is still in the distance. People are less apt to buy since homeowners who have made it this deep into winter without replacing their furnaces will do almost anything to stretch the product a few more weeks. What will you do?...More

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